Remote control tool-VNC

Liu Chao

----VNC software

---- Some network devices and systems are often tested in our labs. During the tests, we will build a network environment to simulate practical applications, the network devices and systems are tested. In each system, multiple client PCs are used to simulate network access to the client. Due to space and cost constraints, each system does not configure a complete set of I/O devices, including the keyboard, mouse, and display, for all client PCs, in this way, managing and maintaining these client PCs becomes a problem. At present, the most popular way is to share an I/O device through the KVM (keyboard, display, and mouse) shared device. Although this problem can be solved, however, a large number of connections from KVM to the client become a new problem. In addition, when debugging the test environment, we need to constantly shuttle between different client PCs and consoles to complete a test, which often makes our engineers exhausted.

---- Many system administrators may encounter the same problem. During a large-scale virus attack and system update, the system administrator often needs to perform operations on nearly PCs, which often leaves them overwhelmed, is there a way to use the existing network to centrally control and manage the client PC? The answer is yes.

---- Remote control software can solve the above problems. It uses software to achieve centralized remote control of computers, reducing users' hardware investment and connections. Many remote control software have emerged in the market, such as Symantec's pcAnywhere, laplink's laplink gold, and expertcity's GoToMyPc, which provide remote control software on the Windows platform, some of them are powerful software. To improve the manageability of windows, Microsoft has also established a multi-user graphical terminal service. For various reasons, these software did not provide a good cross-platform solution. If our control end and the controlled end run different operating systems, these software would be "useless.

---- The emergence of VNC provides us with a new choice. Its full name is virtual network computing, originated from the thin client-ATM network computer developed by at&t Cambridge laboratory. An ATM network computer is a machine running in a Fast ATM network environment with a hand-written input and LCD display. It connects to a high-performance host through the same protocol as VNC to display the host desktop, it does not perform any operations.

---- VNC is a software system that implements the computer mode of the ATM network through software. It is a remote control software developed by at&t and is distributed under the terms of GPL, that is to say, it is an open source software. After the corresponding VNC software is installed on the computer in the network, you can establish and cancel management control on the remote computer at any time on the computer. Therefore, the software is named "Virtual Network Computer ". Since the communication protocol RFB (Remote fram buffers) used by VNC is an open protocol, VNC will soon be transplanted to different platforms by many enthusiasts. The supported operating systems include all Windows 9x/2000/NT/XP, MacOS 8.5 and later versions, and most Unix systems, including Linux. All VNC versions on different platforms, whether server or client, support the communication protocol RFB of VNC. This makes it easy for different platforms to operate on each other.

---- VNC usually works on the server/client. Next we will test the VNC Server and VNC Viewer (client.

----VNC Server

---- The same as all S/C (server/client), The VNC server must work properly, and the remote controlled machine must work properly in the operating system and the TCP/IP protocol stack, it can be remotely controlled only when an accessible IP address is available and the VNC Server is started. We tested and tried it on Windows, Mac OS, and UNIX.

---- On Windows, VNC has downloaded the complete installation package on the homepage of at&t Cambridge lab, including VNC Server/Viewer. Like common software, after setup, all necessary files are copied to the hard disk and a program group is created, "Install VNC Server as service" can add the VNC Server to the System Service of Windows 9x/NT/2000/XP. You can start the VNC server before logging on to the system, start the VNC Server Service in the service control panel and set an access password. The Windows Server is ready.

---- On Mac OS, The VNC Server is installed the same as the common Mac OS software, but after the software is installed, you need to add a vncpatch to the system and restart the machine, you can start the server and set the access password. The working structure of NC server in Windows/Mac OS is shown in Figure 1.

---- On the UNIX platform, the VNC Server works in a UNIX System in a great way different from Windows/MACOs. On the Windows server, the frame cache of the entire graphic console is copied, in addition, the control input from the client is returned to the system, and RFB is used to transmit the frame cache content to the client for display. in UNIX, the most common GUI structure is based on the X-Windows protocol, see figure 2.

---- In UNIX, for previous x applications, VNC directly acts as the X-server and converts the content to be displayed to RFB, when connecting to the remote VNC Viewer, you can directly process client operations to achieve higher efficiency than Windows/Mac OS.

---- The working structure of the NC server in UNIX is shown in figure 3.

---- The VNC Server in UNIX does not need to install the software. You only need to download the binary executable file package that conforms to the unix version and hardware structure on the VNC webpage and unbind it as root locally, run the xvnc script, which prompts you to enter the access password, and then enters the background to run as a service, just like the VNC Server of windows. You can also enter the desktop Number of X-server for accessing the client. If there is no suitable binary executable package for the system, you can download the source code and make some adjustments based on your system. After compilation, you can run the program.

----VNC Viewer (client)

---- The VNC Viewer on all platforms is a small execution file, usually kb ~ Between kb, you can copy it to a floppy disk and carry it with you. In UNIX, VNC Viewer usually requires the support of X-server, and VNC Viewer in Gui environments such as Microwindows and phonto. You can select a suitable client based on your running environment, after starting the client, you only need to enter the IP address of the machine you want to remotely control. After connecting the remote machine to the VNC Viewer, enter the access password, and the desktop of the other machine appears on the screen. If it is a Windows/Mac OS server, you will see a familiar Windows/Mac OS desktop. If it is a UNIX operating system, you will see an X-Windows interface, if X-Windows is xfree86, the default window manager will be TWM. You can operate on the remote machine as you would locally. VNC Viewer can connect to and manage multiple remote hosts at the same time, in this way, you can easily control multiple machines at the same time.Figure 4AndFigure 5In order to manage an Apple computer running Mac OS on Linux and a PC running Windows on Linux.

---- VNC can also work in another "passive connection mode", which is a very useful feature when you need to connect to a machine behind the firewall, you can enable the VNC Viewer to enter the listen mode, so that the VNC server can connect to the VNC Viewer in the opposite direction of the normal mode to bypass this obstacle, just like the normal method, it is very convenient to control remote machines.

----Trial postscript

---- Some problems still exist in actual use. If the operating system or network on the control side cannot work normally, it cannot be controlled. In this case, local management is required on the machine. However, among the many remote control software we have tried, VNC is the most efficient and occupies the least system resources, moreover, it is the only free software that can span multiple platforms. It is the best choice for professional personnel who often need to perform management and maintenance across multiple platforms.